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Hey. My first post here. Just bought my first Lexus. I have a weird problem. When starting the car, and not turning on the lights, the lcds and button etc on the center console are lit up. But when turning on the lights, the center console lights turns off? It is frustrating when driving at night.
Thank you guys. The car is a 1993. I don’t think the lights are modified in anyway. The brightness adjuster only work on the instrument needles, not the background lights
Thank you guys. The car is a 1993. I don’t think the lights are modified in anyway. The brightness adjuster only work on the instrument needles, not the background lights
So only needles are OK to control. How about other part of the cluster meter unit (background)? Does other part completely turn off? If so, the CCFL driver circuit for backgrounds is not working well enough. There are 2 driver circuits. 1 for needles and the other for the background. Both of these go into the dimming mode when turning on lights at night. The dimming is done changing the on/off duty lower. The duty is controlled by the rheostat but it seems to be only effective to the needle's CCFL driver. The driver for the background seems to be stopped when dimmed. I'm an EE guy and there may be a way to fix but without analyzing the circuit myself, it's difficult to say the detail.
So only needles are OK to control. How about other part of the cluster meter unit (background)? Does other part completely turn off? If so, the CCFL driver circuit for backgrounds is not working well enough. There are 2 driver circuits. 1 for needles and the other for the background. Both of these go into the dimming mode when turning on lights at night. The dimming is done changing the on/off duty lower. The duty is controlled by the rheostat but it seems to be only effective to the needle's CCFL driver. The driver for the background seems to be stopped when dimmed. I'm an EE guy and there may be a way to fix but without analyzing the circuit myself, it's difficult to say the detail.
The lights in the instrument cluster stays on. It only the lighting in the center console that turns off when turning lights on. But does this background driver control instrument lighting and lights in center console? Than you for answering yamae
Just want to share this diagram and some wiring from the 1993 manual to aid with Yamae's explanation:
Thanks CELSI0R for the diagram.
I'd check the signal line indicated by a red arrow first and next comes the line with a blue arrow when the light switch is turned ON/OFF.
One simple idea to fix the problem temporarily is to add a resistor between the pin #10 and #4 of the Rheostat Light Control unit. This makes a current bypass. There goes more than a few hundred mA and you have to be careful for the wattage and the heat dissipated. I'd try 10 Ω/10W resistor first. If it were difficult to obtain a resistor, I would try to use a bulb for the brake light.
Last edited by Yamae; 06-04-22 at 07:12 PM.
Reason: to add an idea to fix temporarily.
Thanks CELSI0R for the diagram.
I'd check the signal line indicated by a red arrow first and next comes the line with a blue arrow when the light switch is turned ON/OFF.
One simple idea to fix the problem temporarily is to add a resistor between the pin #10 and #4 of the Rheostat Light Control unit. This makes a current bypass. There goes more than a few hundred mA and you have to be careful for the wattage and the heat dissipated. I'd try 10 Ω/10W resistor first. If it were difficult to obtain a resistor, I would try to use a bulb for the brake light.
Thank you guys. I have been trying a few different thing now. So, i took out the ashtray (the light in ashtray was also not working). Checked the bulb, was ok. Both of the yellow wires that go to this bulb have + power? So I tried something. While having the connector attached to the bulb, I tried to ground one of the yellow wires that go to the bulb (used the ground for the cigarette lighter) and tada! Everything works, lights in buttons, ashtray,displays, everything. Only works with one of these yellow wires, if I ground the other one, tail lamp fuse blows. So I am just wondering, what causes this?
Saw I wrote in the first post here that buttons were lit up when not turning lights on, that is wrong. They have never been lit as long as I owned this car. First time I have seen everything work, when tying to ground this circuit.
Ever seen something like this @Yamae ? Will I hurt anything if I connect I to ground?
Which line are you going to ground?
If you mean the line with the blue arrow, it will force bulbs to light up brighter than normal. Use at least a 10 ohm resistor in series to avoid the excess current.
Which line are you going to ground?
If you mean the line with the blue arrow, it will force bulbs to light up brighter than normal. Use at least a 10 ohm resistor in series to avoid the excess current.
i am connecting one of the wires that go to the ashtray light, to ground
05-31-22, 02:03 PM
93 ls400, lights in center console turns off
